Conservation is a broad term and can be almost interchangeable with the idea of the environmental movement as a whole - almost all environmentalists want to conserve the natural environment.

Conservation is also probably the oldest idea in the environmental movement. Although their aims might not seem particularly at one with those of the current green movement, the Norman kings of England passed laws in the 11th Century to protect hunting forests so they, and they alone, could enjoy their passion for blood sports without their prey being inconvenienced by hungry peasants and their desire to hunt for the pot and fence in land for farming.

In fact, ideas which are at the heart of modern environmentalism have a very long history in religion.

Taoism, the main Chinese religion, preached that man should live in harmony with nature. In India, Jainism preached non-violence to all other creatures: Jainists are vegetarian and won't eat root vegetables, because to uproot them is to kill the plant and monks of the faith are famous for the care they take when sweeping their temples so as not to harm even the smallest fly.

In the West, it's not hard to see that for Christians who believe their God created the world it might not be the best way to worship that creation by wiping it out. The 12th-13th Century hermit St Francis of Assisi is well-known for preaching to birds and animals and has been made the Catholic Church's patron saint of ecology.

Many modern conservationists have found inspiration in these ideas, and those of other societies, for example the Native Americans (Native American) and Australian Aboriginals (Aboriginal) who they believe have had a more harmonious and less exploitative relationship with the natural world, while still relying on it for their livelihood. In fact, modern scientists today are looking to ancient civilisations for wisdom about how to conserve the natural environment. (Scientists look at aboriginal land management).

The modern conservation movement has its roots in the 19th Century, and it's not possible to provide a full survey here. But among the philosophical giants of the movement are the American writer Henry David Thoreau, who is often referred to as the Father of Environmentalism, and the British designer and thinker William Morris, who saw the industrial cities of the Victorian age as unnatural and alienating man from nature.

By 1872, the American Government had founded what is regarded as the world's first national park at Yellowstone. And President Theodore Roosevelt - a famous huntsman - passed much legislation to protect the national environment. When, in the 1930s the dustbowl crisis led brought real environmental disaster to the United States the push to protect the environment became stronger.

In Britain, the first four national parks were established in 1951 by the National Parks and Access to the Countryside Act 1949, which also set up the first national policies on nature conservation.

By 1972, the United Nations had founded its own environment programme which now includes the World Conservation Monitoring Centre (WCMC).

Conservation charities

While governments have been key in carrying out conservation legislation, much work - both campaigning and lobbying and more practical conservation projects - has been down to charities and non-governmental organisations.

The largest and most famous is probably the World Wildlife Fund, now just WWF, with its instantly recognisable giant panda logo, probably the most 'famous' endangered species in the world. WWF was founded in 1961 after valuable groundwork by Sir Julian Huxley, the British biologist who had already played a key role in founding the International Union for Conservation of Nature (IUCN), the world's first global environmental organisation.

Huxley had been shocked by the threats to African wildlife he had witnessed while working for UNESCO and his writing in British newspapers led to the WWF's founding document the Morges Manifesto.

Conservation charities have often grown up around single species seen to be under a particular threat. These creatures tend to be those that will catch the public's imagination and hence their donations: large primates, big cats and whales for example; while you'll struggle to find a major beetle conservation charity.

Examples: Whales and Dolphins. Tigers.

Some have relied not only on charismatic species to raise cash but also on enormously driven individuals who have become personalities far beyond the confines of the biological or botanical sciences.

Two women, Joy Adamson and Diane Fossey, became international stars as a result of films based on their conservation work. Both were murdered in the African landscapes they had fought so hard to protect.

Adamson lived in Kenya and when her husband, game warden George Adamson, shot a lioness in 1956 the couple adopted her cubs. The story of Elsa, the first lion successfully re-released into the wild from domestic captivity became a best-selling book Born Free and later a hit film. The Born Free Foundation still works in conservation today and has broadened the scope of Adamson's work to encompass many species and to campaign for the phasing out of zoos. Adamson was murdered in Kenya in 1980.

Dian Fossey lived and worked with mountain gorillas in Rwanda becoming a world authority on these endangered creatures. She became closely involved with the gorillas - naming them - and wrote a best-selling 1983 account of her work called Gorillas in the Mist which was filmed with Sigourney Weaver playing Fossey. She was murdered in 1985 and conspiracy theories surround her death, which was first attributed to poachers but which some say was carried out to stop Fossey interfering in tourism exploitation of the gorillas or even her sometimes difficult relationships with local people. The Dian Fossey Gorilla Fund International now works to protect the mountain gorillas and also to improve the lives of people who live near their habitats.

Zoos and conservation

One way to conserve a species threatened with extinction in the wild is to keep specimens in captivity. However, zoos are not always loved by environmentalists and conservationists. Most object to zoos on animal rights grounds; believing that it is simply wrong to 'imprison' wild animals for our entertainment or education.

But zoos have reacted to this criticism and almost all now do work in conservation of species in the wild and scientists recognise the valuable work zoos can do in complementing conservation in the natural world.

Broader aims - conserving the whole environment

While conservation has sometimes been associated with particular species, as time has passed the focus has tended to widen to envelop the whole environment - a species cannot survive if its habitat is destroyed.

The study of biodiversity has also made us more aware of how complex are the systems on which life depends.

While a tiger or elephant may capture the imagination and thus the cash, we have come to a greater understanding of how reliant creatures at the top of food chains are reliant on everything beneath them. And, at the top of the whole pyramid sit human beings - on top perhaps, but certainly not removed from.

For example, the charity Conservation International, aims not to preserve environments but to make conservation a part of everyday life.

Conservation and Climate Change

Climate change has changed everything and there is now a pressing new reason for conserving some of our most important habitats which are being recognised not just as natural wonders but as an important resource in storing carbon.

Rainforests in particular are seen as important carbon stores which must be protected to alleviate the effects of carbon change.

Conservation and Economic Development

One of the problems conservationists face is that most of the habitats and species they are trying to protect are in the third world where populations are desperate to escape from poverty and exploiting the resources around them is the most obvious route to do this.

It's not hard to see how conservation efforts coming from developed countries which have comprehensively trashed their own environments and indeed, many would argue, grown rich on appropriating natural resources from their third world colonies, might elicit a mixed response from people who now wish to share in that wealth.

One of the most publicised examples of third world industry feeding first world demand for products and coming under pressure from first world conservationists is the palm oil trade.

Orangutans have been driven to the brink of extinction by the destruction of their south-east Asian rain forest homes for timber and oil palm production. Palm oil goes into hundreds of products enjoyed by western consumers and it's also being studied as a possible biofuel to replace oil.

The challenge for conservationists is to balance protecting habitats with allowing desperately poor people to make a living.

Making rich habitats more profitable intact than they are destroyed is one way of doing this, either through subsidies or by encouraging industries which rely on the preservation of habitats, such as so-called ecotourism.

What can you do?

It's not hard to find charities to support conservation work and if you can afford to support their work it's a great way to help endangered species.

The shift in conservation has been towards focusing on the wider natural world rather than individual species and here your power as a voter, citizen and consumer can be used.

You need to be informed, so prepare to do a little homework, how to buy products which don't harm habitats on which endangered species rely.

Write to your elected representatives and let them know that you are concerned with conservation and their support for it is one way to win your vote. By joining pressure groups you give your voice the power of a chorus, so look at what groups are active in your country and how you can help them.